Doctoral dissertations

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Synthesis, characterization and study of the properties of zinc oxide-based nanocomposites
(Université de M'sila, 2021) Benrezgua Elhadj
: In the present work, pure ZnO and copper-doped zinc oxide (CZO) thin films at different contents (x) were synthesized by sol–gel spin coating process and investigated using various techniques. All samples exhibited a polycrystalline with wurtzite hexagonal phase. The grain size increased and changed its growth mode from c-axis growth to lateral one and the surface morphology was strongly influenced by Cu doping. Optical properties of CZO thin films were investigated. As x increased, the transparency of films was generally increased in the visible region and the band gap energy (Eg) presented a slight shrinking. Ferromagnetic phase was adopted within density functional theory corrected by Hubbard method (DFT+LDA+U) to investigate the properties of pure and CZO structure. The closest Cu impurities gave the more stable configuration. Cu3d states were distributed around Fermi level inducing a major contribution to the magnetic moment. A mix of ionic and covalent bonding was remarked. DFT+LDA+U enhanced significantly the calculated Eg, which presented a narrowing with x. The imaginary part of the dielectric functions presented three main peaks and the static dielectric constants were slightly influenced by Cu doping